Cold case investigators converged on the two Warwick properties today assisted by regional detectives and Crime and Corruption investigators.

"We believe the search of these properties may help us corroborate crucial information gathered during this renewed investigation," Detective Superintendent Steve Holahan of the Homicide Group said.

Investigators received significant new evidence as a result of the appeal made by Barbara's family with homicide detectives on the 40th anniversary of their disappearance in January this year.

"Detectives have interviewed potential witnesses across Queensland, New South Wales, South Australia and Victoria and have uncovered compelling new evidence surrounding events that took place on the day of their disappearance and subsequent murders," Detective Superintendent Holahan said.